A block polymer, in which two or more segments which differ in property are chemically linked, has been known to exhibit excellent physical properties. For example, in a case where a specific block polymer having segments compatible with respective phases of a mixture of incompatible resins is added to the mixture, the block polymer serves both as a compatibilizer which controls a morphology of a dispersed phase by acting on an interface between the phases of the mixture and as a modifier which improves physical properties, such as impact resistance, of the mixture.
It has been known that, in a case where olefins are polymerized under a proper condition with use of (i) a polymerization catalyst containing a specific transition metal compound and (ii) a specific organometallic compound (organoaluminum compound, organozinc compound, organogallium compound, or the like), reversible chain transfer polymerization proceeds, that is to say that a growing polymer chain reversibly transfers, between the transition metal compound, which is catalytic active species, and the organometallic compound. By making use of the reversible chain transfer polymerization, it is possible to synthesize an olefin block polymer.
For example, Non-patent Literature 1 and Patent Literature 1 disclose methods for obtaining an olefin block polymer by solution polymerization performed with a transition metal compound and an organoaluminum compound or an organozinc compound by use of polymerization tanks containing respective olefins differing in composition and are connected in series. Patent Literature 2 discloses a method for obtaining an olefin block polymer by sequentially adding, under equivalent polymerization conditions, two transition metal compounds which differ in copolymerizability.